Screw type catapult



L.J.MAXSON ETAL June 25, 1946.

SCREW TYPE CATAPULT Filed Aug. 22, 1938 4 Sheets-Sfieet 1 p INVENTORS L/SLE J AIAXSON BYFREDERICK s. GROSS ATTORNEY June 25, 1946. J MAXSON HAL 2,402,654

SCREW TYPE GATAPULT Filed Aug. 22, 1958 4 Sheets-Sheet 2 L/SLE J. MAXSON BYFREDERICK B. cnoss ATTORNEY June 25, 1946. L."J. MAXSON ET AL 2,402,554

' SCREW TYPE CA-TAPULT Filed Aug. 22, 1958 4 Sheets-Sheet 5 INVENTORS L/SLE J MAXSON 65 BY FREDERICK B. snoss L. J. MAXSON ET AL June 25, 1946.

SCREW TYPE CATAPULT Filed Aug. 22, 1938 4 Sheets-Sheet 4 INVENTORS L/SL E J MA XSON BY FREDERICK B. GROSS ATTO R Patented June 25, 1946 2,402,654 SCREW TYPiibA'rArULr Lisle J Maxson, United States Navy, and Frederick B. Gross, Langley,-Ya.

Application August 22, 1!}38, Serial No. 226,108

2 9 claims. '(C'L 244 6.?) (Granted under the act or March 3, 1883; as

I a rotatable screw thread.

A further object of this invention is to provide a catapult screw for launching an aircraft, which catapult screw is hollow and likewise serves as a pneumatic reservoir for storing the pressure to. actuate the pneumatic engine which rotates the screw.

Still a further object of thisinvention is to provide a screw advanced aircraft carriage for launching the aircraft at the end of its run, which carriage is retractible by reversing the operation of the screw. 2

A further object of this invention is to provide an acceleration shock absorber between the aircraft carriage and the screw saddle so as to smooth out the starting shock and to further provide bufier means, the greater part of which is mounted on a stationary support and the smaller part of which is borne by the carriage so as" to smooth out the stopping shock.

With the foregoing and other objects in view, the invention consists in the construction, combinatlon and arrangement of parts hereinaiter described and illustrated in the drawings, in which,

Fig. 1 is a side elevational view of the catapult screw and. the screw rotating pneumatic engine end of the screw.

Fig. 2 is a schematic view, partly in section, of the middle portion of the screw, being substantially a continuation of that shown in Fig. 1.

Fig. 3 isa similar view of the launching end of the screw, being a continuation of the portion shown in Fig. 2.

i Fig. 415 atop plan view of the portion of Fig.

2, also showing the turntable track.-,

Fig. 51s a similar top plan view of -the launching end of Fig. 3.

Fig. 6 is a side elevational view of the catapult leessn' l ne if? Q F a 'amended'April 30,1928; 370 o. G. 757) Fig. 9 is a sectional view on line 99 of Fig. 1, showing the trigger cocking cam.

Fig. 10 is a sectional view on line Ill-Ill of Fig. 1.

Fig. 11 is a partly broken away view of the firing valve closing cam.

Fig. 12 is an'eleva'tional view of the end of ilzj he pneumatic operating engine on arrow I2 of Fig. i3 is a sectional view showing a detail for securing the screw cylinders together.

Fig. 14 is a fragmentary view on line I l-44 of F 13. i

Fig. 15 is a sectional view through one of the thread lubricating pencils.

Fig. 16"is a fragmentary elevational View of one of the screw cylinder reservoir supporting rollers; and

Fig. 17 is a fragmentary view of an alternative form of screw supporting roller.

There is shown at 20 the base on which the catapult is supported. This base 20 is itself supported on a turntable 2| rotatable over a circular trackway l8, whereby the direction that the catapult and base '20 may point may be controlled atwill.

Supported at one end of the base 20 is a reversible pneumatic engine 22 of conventional and well known construction, the rotor 23 of which is securely fastened at 24 .to one end of a long, hollow screw-threaded cylinder 25, this screwthreaded cylinder 25 being some sixty feet, more or less, in length. This scr'wwthreaded cylinder 25 may be made in one piece or, for convenience, may'bemade in several sections 26 and2l, each provided "with projecting oppositely threaded necks 28 and 29 secured together by a cylindrical shaped nut 39 provided with internal threads 3| which cooperate witnthe threads on the necks 28 and 29 todraw the same together in pressuretight and leakproof'contact. The cylindrical nut 30 maybe provided withwells 32 to receive a suitable wrench for tightening the same. The outsidediameter of thecylindrical nut 30 is equal ,to or less than thefdiameter at the thread root rollers :35 thus supporting the screw-threaded cylinder 25 at a point a substantial distance below a horizontal diameter. As many sets of rollers may .be provided'as there are joining nuts 30 inthe length of the screw-threaded cylinder 25.

Additional supports may be provided as desired by means of rollers 38, whose surface 31 is cut into screw threads or teeth which may be rolled into and out of the screw threads. The screw threads on the cylinder 25 may be made continuous, either bymakin-g the entire length of the cylinder in one piece or by providing the outer surface of the joining nut 30 with screw threads matched up with the screw threads on the cylinder 25.

Mounted for advancement along the screwthreaded cylinder 25 is a saddle 38 provided with l a great plurality of screw threads cooperating cylinder 25 is hollow and acts as a pneumatic reservoir-for the air pressure of anywhere from 1000 to 3000 pounds per square inch for operwith the screw threads on the cylinder 25.- This saddle encompasses the screw-threaded cylinder 25 more than 180 degrees, but slightly less than the amount between the rollers .33, whereby the saddle cannot jump off the screw-threaded cyl inder 25 yet can freely pass the rollers 33. The length of the saddle is several times the width of the joining nut 38, thus allowin the saddle 38 to continue along the several sections of the cylinder 25 without difficulty. Each screw thread "of, the saddle 38 is provided with a replaceable graphite pencil 40, held in position by a spring-4| beneath a plug 42, thereby lubricating the screw threads on the cylinder 25 every time the saddle passes thereover.

A carriage 43 is slidably supportedby. sliders 44 on a pair of tracks 45 extending along opposite sides of the top of the base 20., This carriage 43 is provided at its front end with depending feet 48 which depend in front of a pair of yieldable buffer members 41 onthe saddle 38, the carriage 43 being provided with a pair of T shaped grooves 48' slidably receiving T shaped tracks 48' of the saddle 38 therein. .As will be apparent, rotation of the screw-threaded cylinder 25 in one direction causes the saddle'to advance. The buffer-'41 yieldsslightly. premitting the feet 46 to contact against the sides of the saddle 38 and be drawn along thereby, the buffer 41 thusabsorbing part of the shock of starting. At the end of the base 20 the saddle .38 will run beyond the screw-threaded cylinder 25 and the carriage 43 may. then be stopped by means of small buffer pistons 48, yieldably mounted thereon and adapted to contact large buffer pistons yieldably extending from the large bufier 50 mounted on the end of the base 20. The small.

bufier pistons 48 assist in absorbing the stopping shock and allow the large buffers 48 time to get into motion and start absorbing the principal portion of the momentum, it being realized that when the carriage 43 reaches this position it will be travelling at the rate of 75 knots, more or less. v

After the cylinder 25 has ceased rotating it may be reversed to withdraw the carriage and-saddle to the initial launching position. To do so, ascrew-threaded toe yieldably carried in a bracket 52 on therear of the center of the carriage 43 is depressed by means of a handle 53 against the spring 54, thus serving to draw the carriage 43 and the saddle 38 back to the-initial position. The carriage 43 is provided with a T groove floor 54' to whichmay be secured a suitable-aircraft launching cradle (not shown) a suitably increasing speedso thatthe aircraft releasing it atthe end of the-- ating the engine 22, according to the sizes of the aircraft to be launched. The air is supplied and replaced in the cylinder 25 by means of a supply pipe 51. extending under the cylinder 25 from one end thereof through'a suitable rotatable fittin 58. This supply pipe 51 is provided with a connection 59 leading through the axial center of the turntable 2| and a suitable fitting and conduit at through cut-Orr valves: to any suitable compressed air supply. This same pipe 51 extends beyond the connection 5811c lead the cylinder pressure through a pipe 63 and past a firingvalve 64, which is connected by aline to the engine, a 4-way valve 61 serving 'as a reverse valve for disconnecting the lines 85 and 68 and connecting the reverse or retractin'gline 68 to the pressure line 88fwhich'is tapped in at 10 to the cylinder pressure line 63.

Connected into the retraction pressure 'line 88 isathrottle valve H for controlling the speed of the engine 22 in reverse and'ior retracting the carriage and saddle. The firing valve 64 serves to admit full pressure of the cylinder to thefengine to operate it atmaximurn'speed. When the carriage, and saddle have reached the end of their run it is desirable that the firing valve 84 be cut oil immediately to save useless waste of' air pressure and to stop the rotation of thescrew-threaded cylinder 25 as quickly as possible,in order that it may be reversed to withdraw the carriageand' saddle to initial launching position, ready for another operation. To do so, the engine 22 is provided with an exhaust line 12 which discharges into an'exh'aust chamber 13. The other end of the exhaust chamber 3 is'open to the atmosphere but is provided with a valve seat '14 against/which may'close a valve face 15 on a con nectingro'd 16 whose end has a pin and slot connection 11 to a crank" connected by link 19 to a bell crank lever 88. The valve seat 14 and valve face I5 are provided with suflicient openingssoi thatthere is no back pressure when the exhaust irom'pipe 12 discharges into the chamber 13' and to the atmosphere while the valve is inopenposition. In closed position, however,' 'the 'valve'face l5 and valve seat prevent any 'quick'e'scape of exhaust to the atmosphere; thereby creating" cam 82 is mounted on :a rotatable .rod'84' provided with a grooved trackway-"85into which extends.

a tooth 88 on the carriage 43. The groovedtrackway 85 extends paralleltdthe pathof thebarriage 43', except when it; approaches ver close to the final launching endwhere it is-curvedfas at 85 to cause the rod 84 and cam'82to' rotate;

ii i li hl' nflinfl the u -awev-mrtion as i to r is aoa .wlth he wl 3 and t u el as g t When -S9re1eased a; spring .81 anchored against abracket 88 pulls a connecting rod 89 secured to he :belle nk lev r he-firing valve is provided w th, a lever wh ch s ltte b th bell crank lever, 89 to .moyeit to the battery or closed position 9|. This lever 90 is provided with a lanyard 92 for moving the control valve 64 from battery position to firing position.

In operation, the carriage and saddle are placed at initial launching position adjacent the engine 22 with breakable link 54 in anchoring position. The bell crank lever 80 is placed in position with the pawl 8| against the face of cam 82 and the exhaust valve 14 in open position within the exhaust chamber 13, the valve 61 being placed in position, connecting pressure line 65 to the advanced operating line 66 to engine 22. The lever 90 is placed in battery position 9| and with the aircraft properly positioned on its cradle on carriage 43 the lanyard 92 is pul ed to move the ev r 90 from position ill to position 90 against the bell crank lever 80. This admits the pressure from the cylinder 25 to the engine 22, operating it in an advancing position, rotating the screw-threaded cylinder 25 to launch the aircraft by causing the saddle and carriage to travel to the other end thereof. At the other end the buffers come into operation, stopping the carriage and saddle and allowing the aircraft to be catapulted away into the air. As the carriage approaches the end of, its travel the tooth 86 rotates cam 82 and releases bell crank lever 80 to close off the firing valve 64 and simultaneously close the exhaust chamber valve 14, thus stopping the rotation of the engine 22.

To retract the carriage and saddle, the threaded toe i pressed down into contact with the screw-threaded cylinder 25, the valve 61 is shifted to connect the tank pressure line 69 to the engine retraction line 68 and the throttle valve ll operated to control the speed of retraction. Once the engine 22 has come to a stop, the built-up back pressure in the exhaust chamber 13 will escape, due to a small clearance still left within the exhaust chamber between the valve H and its face 15. When the carriage and saddle have been retracted to initial position, the catapult is ready for another identical operation.

Other modifications and changes in the proportions and arrangements of the parts may be made by those skilled in the art without departing from the nature of the invention, within the scope of what is hereinafter claimed.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

Having thus set forth and disclosed the nature of this invention, what is claimed is:

1. An aircraft launching catapult comprising a rotatable constant pitch multi-thread screw and an aircraft catapulting means advanceable along said screw, said aircraft catapulting means comprising a screw saddle partially embracing said screw, a carriage slidably mounted on said saddle, and starting shock buffer means between said carriage and said saddle.

2. An aircraft launching catapult comprising a pneumatic engine, a rotatably mounted longitudinal cylinder secured to said engine, a constant pitch multi-screw thread extending about the longitudinal surface of said cylinder, and an airlail tir e th ea g q 3. An aircraft launching catapult comprising a pneumatic engine, a rotatably mounted longitudinal cylindersecured to said engine, a screw thread extendingabout the longitudinal surface of said cylinder, an aircraft catapulting means advanceable alon said screw thread, said screw threaded cylinder being hollow and providing a pneumatic pressure reservoir therein, and controllable means connecting said reservoir to said pneumatic engine for transmitting the pressure of the reservoir to said engine at will.

4. An aircraft launching catapult comprising a base, a screw type aircraft catapulting means mounted on said base, said screw type catapulting means comprising a hollow cylindrical rotatable screw providing a pneumatic reservoir therein, aircraft carrying means advanceable along said screw and a pneumatic reversible engine at one end of said base for rotating said cylindrical screw and controllable means connecting the reservoir within the hollow screw to the engine to cause the engine to rotate the screw in either direction at will.

5. An aircraft launching catapult comprising a base, a turntable on which said base is mounted, a screw type aircraft catapulting means mounted on said base, said screw type catapulting means comprising a hollow cylindrical rotatable screw, aircraft carrying means advanceable along said screw, a pneumatic reversible engine for rotating said cylindrical screw, said hollow cylindrical screw providing a pneumatic pressure reservoir therein, and controllable means connecting the reservoir to the engine to operate the same in either direction at will.

6. An aircraft launching catapult comprising a base, a screw type aircraft catapulting means mounted on said base, said screw type catapulting means comprising a hollow cylindrical rotatable screw providing a pneumatic pressure reservoir therein, aircraft carrying means advanceable along said screw, and a pneumatic engine at one end of said base operable from the pressure in the pneumatic reservoir within the hollow screw for rotating said cylindrical screw.

7. An aircraft launching catapult comprising a base, a turntable on which said base is mounted, a screw type aircraft catapulting means mounted on said base, said screw type catapulting means comprising a hollow cylindrical rotatable screw providing a pneumatic pressure reservoir therein aircraft carrying means advanceable along said screw, a pneumatic reversible engine at one end of said base for rotating said cylindrical screw, and a controllable means for utilizing the pneumatic pressure from the reservoir'in the screw for operating the engine in either direction at will.

8. An aircraft launching catapult comprising a base, a screw type aircraft catapulting means mounted on said base, said screw type catapulting means comprising a cylindrical rotatable screw, aircraft carrying means advanceable along said screw, a pneumatic reversible engine at one end of said base for rotating said cylindrical screw, a controllable means for operating the engine in either direction at will, a buffer means at the other end of said base for stopping the advance of said aircraft carrying means after disengagement from said screw and a temporary screw-engaging means on said aircraft carrying means for retracting said aircraft carrying means into reengagement with said screw as said screw is reversed.

craft catapulting means advanceable along said 9.- An aircraft launching catapult comprising a base, a turntable on which said base ispmounted; a screwtype aircraft catapulting means mounted on said base, said screw type catapulting means comprising a cylindrical rotatable screw, aircraft carrying means advanceabie along said screw, a pneumatic reversible engine at one end of said base for rotating said cylindrical screw, 2." controllable means for operating the engine in either direction at will,- a buffer means at the other end of said base 'for stopping the advance of said aircraft carrying means after disengagement from said screw, and temporary screw-engaging means 1 on said aircraftcarrying means for retractin said'aircratt carrying means into reengagement with said screw as said screw is reversed. 1 r LISLE J. MAXSON.

I FREDERICK B. GROSS. 

